Demand for natural gas has created a hydraulic fracturing or fracking boom; since 2008 over 5,000 new wells have been drilled nationwide. Workers at Chesapeake Energy, one of the biggest gas companies conducting fracking, are seen on the job site near Towanda, PA.

Rocks on the shore of the Lackawanna River in Duryea, Pa., are discolored by iron oxide and sulfur compounds — pollutants left behind by past coal mining in the state.

David GilkeyNPR

In Pennsylvania, there's an industrial revolution going on. Battalions of drilling rigs are boring into the earth to extract natural gas from an underground layer of shale called the Marcellus formation.

And as the wells multiply all along the western end of the state, people worry they may be facing another toxic legacy.

The first one came from coal mining. All over the state, you can see bright orange rivers and streams. The aquatic life was killed by acidic runoff from abandoned mines.

"Are we really going to let this happen to Pennsylvania again?" asks David Yoxtheimer, a hydrologist at Penn State who grew up here. "Are we going to make sure that we have enough money and that these companies' feet are held to the fire to make sure that once their operations are done, they put everything back together, tidy it up, and make it look like nothing happened there in the first place?"

Progress isn't always pretty. In the natural gas boom, a lot of the ugliness has to do with water.

An Unexpected Nuisance

Drillers need billions of gallons of water. It's their dynamite: They use it to split rock.

And they need trucks to move that water. Everywhere you drive in Pennsylvania's gas country, you're stuck behind a truck. You get mud all over your car. One-stoplight towns have traffic jams at noon.

Dan Lopata, who's in charge of water for Chesapeake Energy, says trucks are a pain for everybody.

"The transportation of all the fluids is probably our biggest expense, and that's our highest exposure to the local community," says Lopata. "That's what they see driving up and down the road are the trucks."

I asked Lopata if those trucks annoy local people. "I would say yes to that question," he replied.

I visited a Chesapeake Energy well site in the northeast part of the state; it was half the size of a football field. Machinery and workers were everywhere, all surrounded by forest. Deer in the woods, and John Deere on the pad.

To get the natural gas out of the Marcellus layer of shale, engineers drill about a mile deep, then out horizontally through the shale layer. Explosive charges create cracks in the shale. Engineers then mix water with sand and chemicals. Big pumps drive this slurry down into the shale. The fluid is so highly pressurized that it opens the cracks wider and liberates gas.

What comes gushing up is called "flowback," a bubbly mix that looks like muddy champagne. Chesapeake senior director Brian Grove points to the 12-foot-high steel well head that's attached to several big hoses. That's the plug at the opening of the well where gas will emerge. "It will come up through the well head," he explains over the din. "We will then put it through a large-scale separator, which will send water in one direction into steel tanks to be recycled, and then the gas will go in the other direction."

What To Do With Toxic Wastewater?

Flowback is nasty stuff. Grove explains that the water has been exposed to what once was a seabed. "When you expose fresh water to it, you absorb the salts. That is something you don't want to spill on the surface."

Besides salt, the water picks up minerals that had been buried in the rock, some of them toxic and some radioactive, like barium. And it still contains some of the chemicals that engineers add to the frack water, some of which are classified as toxic as well.

This wastewater flows back up out of the well for about a month, but the well will continue to regurgitate a salty brine for years, which has to be collected and disposed of. How the industry handles this wastewater is a controversial issue.

For a while, the wastewater was dumped directly into rivers, untreated. Some drillers shipped it to municipal water treatment plants, which weren't equipped to handle the toxic material in the waste. A current practice is to pump it temporarily into man-made, lined holding ponds. But some of those ponds have leaked. Trucks leaked wastewater as well. And there are the claims, most noticeably made in the HBO documentary Gasland, that backyard drinking water wells were being polluted by drilling.

Grove says the industry should have warned people about the kind of mess fracking can make. "I think the biggest mistake the industry made early on in Marcellus development was just remaining silent," he told me. "I think the industry as a whole has, for 50 or 60 years, operated largely in Texas, Oklahoma, Louisiana. The folks that moved east were people that were not used to having to explain themselves; they were used to being understood."

So, under a lot of public pressure, the state Department of Environmental Protection cracked down. Since 2008, the DEP has tightened rules for holding ponds where frack water is stored, to keep them from leaking. Another big change was to tell drillers to stop running frack water through public water treatment plants.

A New Model For Wastewater: Treat And Reuse

These rules helped create a new business: recycling frack water. Cheseapeake Energy recycles its frack water itself, but other companies send their wastewater to recycling plants such as Eureka Resources in Williamsport, Pa.

Eureka is in an old brick factory next to the Susquehanna River. The first thing you see are water trucks pumping polluted frack water into tanks. I put on a hard hat and went in to talk with plant owner Dan Ertel about this new business.

"We saw an absolute lack of any water treatment businesses or companies here," Ertel says. So in 2008 Eureka modified off-the-shelf technology and set up a factory to clean up the peculiar mix of gunk in frack water. The gunk is solid material like dirt, but also minerals like calcium, barium, sulfur compounds and others pollutants. They also remove any radioactive material that might have come from the shale.

Then drillers take the water — still too salty to go into rivers — and use it again to fracture shale at another well. What isn't recycled goes to waste wells in Ohio or into holding ponds or steel tanks in Pennsylvania. The solid material left over is shipped to landfills, as regulated by state law.

Ertel says now that they can't dump water in streams, more drillers are showing up on his doorstep. "Basically what we're seeing is, we're seeing a gradual, controlled but necessary crank-down of regulation," he says.

Ertel says his company can also put frack water through a more rigorous process so it can go back into rivers. But that costs more. For now, about 90 percent of frack water is recycled in Pennsylvania and then re-used in fracking.

That's an improvement. But that recycled water still requires more trucks to haul it around. Marty Muggleton says it's time to fix the truck problem. Muggleton is vice president of TerrAqua Resource Management, another recycling company in Williamsport.

"Nobody likes them," he says of the trucks. "And nobody likes to pay for them. The communities would like the least amount of truck traffic. The operators would like to allocate the least amount of money to support truck traffic."

Muggleton's company is designing centralized water treatment facilities closer to fracking sites, and pipelines that would replace water trucks.

Following The Frack Water

But no matter how it's moved, it's inevitable that water is going to get spilled. Since 2008, more than 5,000 new wells have been drilled in the state. Those wells have brought with them more than 700 violations of state law related to water, with fines totaling over $1.5 million. And spills tend to take place out of sight — at frack pads up in the woods, or at recycling plants. People worry about what they can't see.

So scientists are trying to see for them. One of them is a hydrologist, Andrew Gavin. He works for the Susquehanna River Basin Commission, and the day I met up with him, he was at a very nice trout stream called Gray's Run. It's surrounded by forest — and a frack site. As we pulled on waders, Gavin explained what the commission was up to.

"What we're doing in this monitoring project is really establishing what the general health is of the streams, so we can measure if there any changes in the quality of the water."

Gavin and his team regularly take "grab samples" of stream water near fracking sites. The commission has also planted battery-powered monitors in over 50 streams. If something unusual gets in the stream, their computers in Harrisburg alert them. There are other groups in the state monitoring stream water around frack sites as well, employing both volunteers as well as scientists.

Over the past four years, the water used for fracking has won more protection. But scientists say they need to be vigilant. Frack water chemistry, for example, can be surprising. Water engineer Jeanne VanBriesen at Carnegie Mellon University points out that bromide in frack water behaved in an unexpected way when it went through public water treatment plants. It reacted with chlorine to create compounds that were potentially hazardous.

"We're not omniscient," she says of water scientists. "We can't see everything, and sometimes there are downstream effects, particularly ones that involve the waste systems that interact with each other."

VanBriesen also wonders about what happens to all the frack water that's left underground. Pennsylvania is already a pin cushion. Oil and gas drilling has gone on for over a century here, long before fracking arrived.

"There are lots of holes in Pennsylvania," she says. "Knowing where the old ones are is very important when you're putting in a new one."

George Jugovic Jr., who runs the environmental group PennFuture, says the location of a lot of those wells is unknown. "We have over 300,000 oil or gas wells that have been abandoned," he says, "that are out there somewhere, that have not been properly plugged and that can serve as conduits for contamination to migrate up into existing groundwater."

Brian Grove of Chesapeake argues that it's unlikely that the water left behind in the Marcellus shale layer could ever contaminate groundwater — it would have to travel upward at least a mile through rock. But a study by the Ground Water Protection Council of fracking water in Texas and Ohio found that water used in drilling has in fact come back up through old, unplugged wells.

Yoxtheimer, the Penn State hydrologist, says fracking has been a "lightning rod" for the nation's environmental movement. And he says Pennsylvania, like it or not, has been a case study for other states, like New York, that are weighing whether to allow hydraulic fracturing. "I think it's been very interesting to watch the industry change its practices because of public pressure," he says.

Pennsylvania's government appears to be listening. There's a new law that charges a fee for each well drilled. The fee is not as high as some wanted, but it should generate millions of dollars for Pennsylvania and the counties where drilling takes place. And the state has also raised the bond amount that companies must post to cover the costs of cleanup once they've left.

Copyright 2014 NPR. To see more, visit http://www.npr.org/.

Transcript

MELISSA BLOCK, HOST:

This is ALL THINGS CONSIDERED from NPR News. I'm Melissa Block.

ROBERT SIEGEL, HOST:

And I'm Robert Siegel.

This week, we're taking a closer look at the natural gas industry and its impact on human health and the environment. In just under a decade, some 200,000 gas wells have been drilled in the U.S. The boom is largely the product of an engineering technique that allows drillers to tap gas reserves that were once unreachable. The technique is called hydraulic fracturing.

BLOCK: Fracking has generated much-needed jobs - about 600,000 of them - and billions of dollars for the U.S. economy. But scientists warn very little is known about how much pollution it's causing. We begin our series in one of the nation's biggest gas hot spots, the vast Marcellus shale that runs through Western Pennsylvania.

NPR's Christopher Joyce reports on the struggle to prevent the region's water from being polluted by the gas industry.

(SOUNDBITE OF FLOWING WATER)

CHRISTOPHER JOYCE, BYLINE: Water is a big deal in Pennsylvania. It's got great trout streams, beautiful rivers. But industry has ruined a lot of Pennsylvania's water. Coal companies hammered this place. Mining left behind acidic water that's killed thousands of miles of streams. I stood on a bridge over a patch of the Lockawanna River and every rock I could see was bright orange.

And now, Pennsylvanians fear a new toxic legacy, this time from shale gas. David Yoxtheimer is a hydrologist at Penn State University.

DAVID YOXTHEIMER: Are we going to let this happen to Pennsylvania again? Are we going to make sure that we have enough money and that these companies' feet are held in the fire to make sure that once their operations are done, they put everything back together, tidy it up, and make it look like nothing happened there in the first place.

JOYCE: New gas drilling companies in the state want Pennsylvania's water to bust open shale. That means, first of all, water trucks. Everybody complains about these, even people in the industry. I visited a truck staging area run by Chesapeake Energy and I talked to...

DAN LOPATA: Dan Lopata, L-o-p-a-t-a.

JOYCE: And you're in charge of the water?

LOPATA: I'm the field superintendent with Chesapeake, in charge of all our water infrastructure, that's correct.

JOYCE: For the Marcellus?

LOPATA: For the whole Marcellus.

JOYCE: That's a lot of water.

LOPATA: That's a lot of water, a lot of trucks. The transportation of all the fluids is probably our biggest expense and that's our highest exposure to the local community. That's what they see driving up and down the road are the trucks.

JOYCE: And that's what they're annoyed with.

LOPATA: I would say yes to that question.

(SOUNDBITE OF WATER TRUCKS)

JOYCE: The water trucks roll up to a Chesapeake frack site, a drilling pad about half the size of a football field on a leveled hilltop. There's machinery and workers everywhere, all surrounded by forest - deer in the woods, and John Deere on the pad. Workers here drill about a mile down, then out sideways into a layer of shale that holds natural gas.

They detonate charges to crack the shale, then they pump millions of gallons of water, mixed with sand and chemicals, down at high pressure to pry open those cracks and release the gas. When the gas comes to the surface, it brings up a lot of that water. And it's pretty nasty.

Brian Grove is a Chesapeake senior director. He explains that the water has been exposed to what was once a seabed.

BRIAN GROVE: When you expose freshwater to it, that water absorbs the salts. That is something that you don't want to spill on the surface.

JOYCE: Besides salt, the water picks up the minerals from the shale, some of them toxic, some radioactive. About a third of that polluted brine comes right back up. But more salty liquid will spew out of the well over a period of years. This wastewater is what makes people really twitchy. That's because industry used to dump the water straight into rivers. And pools holding the waste sometimes leaked. Brian Grove says the industry should have warned people how messy fracking is.

GROVE: I think the biggest mistake the industry made early on in Marcellus development was just remaining silent. I think the industry, as a whole, has for 50, 60 years operated largely in Texas, Oklahoma, Louisiana. The folks that moved east were people that were not used to having to explain themselves, they were used to being understood.

JOYCE: But explaining what fracking looks like may not have satisfied people in the face of this onslaught. Over 5,000 new wells just since 2008 in the Marcellus shale, and there have been close to 700 violations involving water. And those violations have cost the industry a little over a million and a half dollars.

So, under a lot of public pressure, the state Department of Environmental Protection has cracked down. They said no more dumping frack water straight into rivers. So, some companies ran it through public water treatment plants. But the state stopped that, too. It came out just too salty and too dirty. So the industry was forced to find another way to deal with frack water. And that's how the recycling business got started.

(SOUNDBITE OF MACHINERY)

JOYCE: Eureka Resources in Williamsport is in an old brick factory next to the Susquehanna River. I put on a hard hat and went into the plant to talk with owner Dan Ertel about this recycling business.

DAN ERTEL: Oh, you can smell that. That's flowback water. This is where all the flowback (unintelligible) come.

JOYCE: When Eureka started in 2008, the state wasn't ready for all this frack water from the wells.

ERTEL: We saw an absolute lack of any water treatment businesses or companies here.

JOYCE: So, Eureka modified off-the-shelf technology to clean up this peculiar mix of gunk in frack wastewater. There's solid material like dirt, minerals like calcium, barium, sulfur compounds and other pollutants. Then drillers take the cleaned up water back and use it again to break shale in a new well.

All of this is an improvement. But at some point, companies will stop drilling news wells and leave. And the state will have to find a way to get rid of the wastewater that's left behind. And in the meantime, there will be more spills. They tend to take place out of sight, in places people don't go to - a frack site, out in the woods, or on a deserted country road. And people worry about what they can't see. So there are scientists who are out there trying to see for them.

(SOUNDBITE OF STREAM)

JOYCE: I met hydrologist Andrew Gavin at a very nice trout stream called Gray's Run. He works for the Susquehanna Basin River Commission. We pulled on some waders and Gavin explained what he was up to.

ANDREW GAVIN: What we're doing in this monitoring project is really establishing what the general health of the streams so then we can measure, you know, if there any changes in the quality of the water.

JOYCE: Scientists have to know the chemistry of a clean stream now so they'll know if frack water gets into one.

GAVIN: You just keep going until you fill up the sampling container.

JOYCE: The commission Gavin works for has planted battery-powered monitors in over 50 streams. If something unusual gets in the stream, their computers in Harrisburg alert them. So, overall, there has been improvement in the way frack water is handled. But scientists say they need to be vigilant. Frack water chemistry, for example, can be surprising. I heard that from a water engineer, Jeanne VanBriesen at Carnegie Mellon University.

JEANNE VANBRIESEN: We're not omniscient. We can't see everything. And sometimes there are downstream effects, particularly ones that involve the way systems interact with each other.

JOYCE: In fact, that happened in Pennsylvania. Bromide in frack water reacted with disinfectants at water treatments plants and created new compounds that could be hazardous to peoples' health. VanBriesen says she also wonders about what happens to all the frack water that's left underground. Pennsylvania is a pin cushion. Oil and gas drilling has gone on for over a century here. She worries that frack water could seep up to the surface.

VANBRIESEN: There are lots of holes in Pennsylvania. Knowing where the old wells are is very important when you're putting in a new one.

JOYCE: And people don't know where all those old wells are. Pennsylvania's struggle with this new industry is being repeated in other states, where there is gas-bearing rock. Penn State's David Yoxtheimer, the hydrologist who follows the frack water, says this issue has really galvanized people.

YOXTHEIMER: The natural gas industry and fracking has sort have been a lightning rod for America's environmental consciousness.

JOYCE: And although each state with natural gas is unique, one thing is common to all of them - the need for water, lots of it.

Christopher Joyce, NPR News.

SIEGEL: Our series on America's fracking boom continues tomorrow on MORNING EDITION. We'll hear from sick patients living near gas wells in Pennsylvania and from the doctors who are searching for answers. Transcript provided by NPR, Copyright NPR.